Photosensitivity sources of dissolved organic matter from wastewater treatment plants and their mediation effect on 17α-ethinylestradiol photodegradation

Dissolved organic matter (DOM) from each treatment process of wastewater treatment plants (WWTPs) contains abundant photosensitive substances, which could significantly affect the photodegradation of 17 alpha-ethinylestradiol (EE2). Nevertheless, information about EE2 photodegradation behavior mediated by DOM from diverse WWTPs and the photosensitivity sources of such DOM are inadequate. This study explored the photodegradation behavior of EE2 mediated by four typical WWTPs' DOM solutions and investigated the photosensitivity sources of DOM in the anaerobic-anoxic-oxic (A2/O) process. The parallel factor analysis identified three varying fluorescing components of these DOM, tryptophan-like substances or protein-like substances, microbial humus like substances, and humic-like components. The photodegradation rate constants of EE2 were positively associated with the humification degree of DOM (P < 0.05). The triplet state substances were responsible for the degradation of EE2. DOM extracted from the A2/O process, especially in the secondary treatment process had the fastest EE2 photodegradation rate compared to that of the other three processes. Four types of components (water-soluble organic matter (WSOM), extracellular polymeric substance, humic acid, and fulvic acid) were separated from the A2/O process DOM. WSOM had the highest promotion effect on EE2 photodegradation. Fulvic acid-like components and humic acid-like organic compounds in WSOM were speculated to be important photosensitivity substances that can generate triplet state substances. This research explored the physicochemical properties and photosensitive sources of DOM in WWTPs, and explained the fate of estrogens photodegradation in natural waters.

Automated summary

This study investigated the photodegradation behavior of 17 alpha-ethinylestradiol (EE2) mediated by diverse dissolved organic matter (DOM) solutions from wastewater treatment plants (WWTPs). The findings revealed that the humification degree of DOM positively influenced the rate of EE2 photodegradation, with humic-like components playing a significant role. Additionally, DOM extracted from the anaerobic-anoxic-oxic (A2/O) process had the highest photodegradation rate and water-soluble organic matter (WSOM) was found to have the strongest promotion effect on EE2 degradation.